Metal roof structures typically comprise a series of parallel rafter beams extending across the building in one direction, and purlin beams parallel to each other mounted on top of the rafters extending in a direction normal to the rafters. Insulation material in long blankets is placed in the area between purlins. The blankets of insulation material can be laid along the length of the purlins or across the purlins in a direction normal to the purlins. If desired, the roof structure can have a first layer of insulation material which is laid along the length of the purlins, and a second layer of insulation material which is laid laterally across the purlins on top of the first layer of insulation. Sheets of hard roofing material such as metal decking are then attached on top of the purlins over the insulation material. Because the hard roofing material comes in long sheets and the roofs generally have two sloped sections, it is customary to construct the roof along the length of the structure from one end to the other. The workers stand on the previously laid section of the roof to construct the next section.
The insulation material is supported between the purlins beneath the hard roofing material. Various methods of supporting the insulation material have been used. Mounting straps or wire mesh, which are attached to or draped over the purlins forming a lattice, have been used. This is referred to as banding. A support sheet, typically made of vinyl and acting as a vapor barrier, is then rolled onto the lattice, and insulation material is placed between adjacent purlins and over the support sheet. If the installation of the lattice is done from underneath the roof structure, scaffolding or lifting equipment is typically required for installation. Since the lattice encompasses the entire roof, installation is costly and time consuming. Once the hard roofing material is mounted on the purlins, the support sheet can support the insulation material and the lattice no longer serves any useful purpose.
Some systems dispense with the lattice and use the support sheet itself to support the insulation material. The support sheet is dispensed from a roll and draped from adjacent purlins. Insulation material is then placed on top of the support sheet. A carriage, such as that disclosed in U.S. Pat. No. 4,967,535 to Alderman, has been used to aid in the dispensing of the support sheet. The carriage is positioned on top of the purlins and travels in a downstream direction along the length of the purlins during the roof construction. A roll of the support sheet material is mounted on the carriage and the support sheet is dispensed from the roll and placed on top of the purlins. As the carriage travels in the downstream direction, the support sheet is draped across the purlins.
The carriage can be any length up to the width of the roof itself. For example, the carriage can be comprised of a plurality of carriage sections which are joined together so that they span the entire width of the roof. Each carriage section has a roll or a plurality of rolls of support sheet which are dispensed as the carriage travels along the purlins. Preferably, the support sheets are provided with a width appropriately sized so that the support sheet extends between two adjacent purlins. The carriage is then propelled along the length of the purlins so that the carriage sections move in unison.
The carriage can also include a walking platform for workers to stand and walk on during the construction of the roof, such as that disclosed in U.S. Pat. No. 5,653,081 to Wenrick et al. The platform is about a meter wide and extends in a direction normal to the length of the purlins. Each carriage section has a platform section extending the entire width of the carriage section so that when the carriage sections are joined together, a continuous platform is formed. The platform is positioned above the purlins and downstream from the support sheet rolls and the last completed section of the roof. The platform has a railing on the downstream edge thereof, to function as a barrier for the workers from the exposed portion of the roof structure in which the sheets of hard roofing material have not been installed. The carriage sections at the ends of the carriage can have a smaller railing extending across the width of the platform to function as a barrier for the ends of the platform.
Workers can stand on top of the fastened sheets of roofing material which are upstream of the carriage. To protect the workers near the lateral edge of the roof structure, the workers are typically tied off with lines, such as rope or cable, to a portion of the roof structure to prevent them from falling entirely off of the roof structure. Although tying off workers sufficiently protects the workers, the lines can interfere with and be tangled up with the insulation, roofing material, and/or other lines. It is also cumbersome to re-tie the lines as the completed section of the roof advances. Alternatively, a warning line can be set up a distance from the lateral edge of the roof structure, to warn the workers that they are approaching the edge of the roof structure. A temporary barrier, such as a railing may also be set up a distance from the lateral edge of the roof structure. Although the warning lines and temporary barriers are sufficient to warn the workers in the middle of the roof structure, they do not protect the workers who are constructing the roof at the immediate lateral edges of the roof structure.
It would be desirable to have an apparatus and method for safely providing a barrier for the workers working adjacent the lateral edge of a roof structure, which is simple and easy to use and does not interfere during the construction process.